In this photo made on Saturday, March 1, 2014, a truck drives through an intersection in Clarksburg, W. Va. In March of 2013, a truck carrying drilling water overturned near the same intersection onto a car driven by Lucretia Mazzei, killing her two sons, 7-year-old Nicholas Mazzei-Saum and his 8-year-old brother Alexander Mazzei-Saum. An analysis of traffic fatalities in the busiest new oil and gas-producing counties in the U.S. shows a sharp rise in deaths that experts say is related to the drilling boom.

CLARKSBURG, W.Va. — Booming production of oil and natural gas has exacted a little-known price on some of the nation’s roads, contributing to a spike in traffic fatalities in states where many streets and highways are choked with large trucks and heavy drilling equipment.

An Associated Press analysis of traffic deaths and U.S. census data in six drilling states shows that in some places, fatalities have more than quadrupled since 2004 — a period when most American roads have become much safer even as the population has grown.

“We are just so swamped,” said Sheriff Dwayne Villanueva of Karnes County, Texas, where authorities have been overwhelmed by the surge in serious accidents.

The industry acknowledges the problem, and traffic agencies and oil companies say they are taking steps to improve safety. But no one imagines the risks will be eliminated quickly or easily.

“I don’t see it slowing down anytime soon,” Villanueva said.

The energy boom, fueled largely by new drilling technology, has created badly needed jobs, lifted local economies and drawn global manufacturers back to the United States. But the traffic accidents have devastated families: two young boys crushed to death last year by a tanker truck in West Virginia; a Pennsylvania father killed by another tanker in 2011; a 19-year old Texas man fatally injured in 2012 after colliding with a drilling truck on his way to work.

Not all of the crashes involved trucks from drilling projects, and the accidents have been blamed on both ordinary motorists and heavy equipment drivers. But the frenzy of drilling activity contributes heavily to the flood of traffic of all kinds that has overwhelmed many communities.

Deadly crashes are “recognized as one of the key risk areas of the business,” said Marvin Odum, who runs Royal Dutch Shell’s exploration operations in the Americas.

Crashes often increase when the volume of traffic goes up, whether because of an improving economy, a new shopping mall or more people moving into the area. Still, the number of traffic fatalities in some regions has climbed far faster than the population or the number of miles driven.

In North Dakota drilling counties, the population has soared 43 percent in the last decade, while traffic fatalities increased 350 percent. Roads in those counties were nearly twice as deadly per mile driven than the rest of the state. In one Texas drilling district, drivers were 2.5 times more likely to die in a fatal crash per mile driven compared with the statewide average.

This boom is different from those of the past because of the hydraulic-fracturing process, which extracts oil and gas by injecting high-pressure mixtures of water, sand or gravel and chemicals. It requires 2,300 to 4,000 truck trips per well to deliver those fluids. Older drilling techniques needed one-third to one-half as many trips.

Another factor is the speed of development. Drilling activity often ramps up too fast for communities to build better roads, install more traffic signals or hire extra police officers to help direct the flow of cars and trucks.

Last year, a truck carrying drilling water in Clarksburg, W.Va., overturned onto a car carrying a mother and her two boys. Both children, 7-year-old Nicholas Mazzei-Saum and 8-year-old Alexander, were killed.